Dynamics of fine roots and soil nitrogen in Mangifera indica‐based agroforestry systems in the Central Himalayan region, India

Abstract

AbstractThis study estimated seasonal variations among several parameters of the fine roots and N dynamics in Mangifera indica‐based agroforestry systems; we examined homegarden (HG), agri‐horticulture (AH) and agri‐horti‐silviculture (AHS) systems in the Bhabhar area of the Indian Central Himalayan region. Fine roots biomass (FRB) and fine roots production (FRP) of M. indica were highest in the AH system and lowest in the HG system while fine roots turnover (FRT) showed a reverse trend. FRB, FRP and FRT rates decreased with soil depth and distance from the tree base, with larger variations in the AH system. The biomass: necromass ratio varied between 1.91 and 2.42 for HG, between 2.27 and 3.29 for AH and between 2.09 and 2.46 for AHS systems. Among all the selected agroforestry systems, concentrations of mineral N (NH4‐N and NO3‐N) were higher in the AH system and lower in the AHS system while net N mineralization rates were higher in the AHS system. In HGs, FRB it was significantly correlated with ammonification, nitrification and N mineralization while in the AH system it was positively correlated with nitrification and N mineralization. In the AHS system, it was positively correlated with ammonification only. Thus, it can be concluded that in agroforestry systems FRB was enhanced by rapid N mineralization. The variability in FRB and N mineralization between selected agroforestry systems were possibly due to the differences in soil characteristics and management practices. For enrichment of soil nutrients, the contribution of fine roots could be of more importance through the process of decomposition under the prevailing agroforestry systems.